The overall goal of the University of Pennsylvania Udall Center is to address the problem of cognitive impairment in Parkinson's Disease (PD) from bench to bedside. This project contributes to that goal by developing a disease-specific rating scale to measure the impact that cognitive impairment has on daily function. The scale would be appropriate for use in patients with PD and dementia (PDD) and also for patients with PD and cognitive impairments not sufficient to meet diagnostic criteria for PDD. Our proposed rating scale is intended to be an outcome measure for observational studies and clinical trials. There is currently no disease-specific scale to address the impact that cognitive impairment has on daily function in PD, and clinical trials to date have borrowed functional measures developed for use in Alzheimer's disease (AD). However, the cognitive profile of patients with PD is distinct from AD. In addition, patients with PD have motor impairments that affect their daily, function, and may obscure the impact of cognitive impairment as measured by existing scales used in dementia research. Thus, there is a need for a functional rating scale specifically for use in PD patients with cognitive impairment. We propose to develop a new scale, the "Functional Consequences of Cognitive Impairment" (FCCI) scale to address this unmet need. We will take a methodologically rigorous approach to scale development beginning with detailed qualitative studies to generate scale items, followed by psychometric studies to demonstrate the reliability and validity of the FCCI. The first aim of this study is to conduct qualitative studies involving patients and knowledgeable informants to generate a range of items addressing the functional consequence of cognitive impairment that will be used to create the final rating scale. The second aim of this study is to undertake detailed psychometric testing of the reliability and internal consistency of the FCCI. The third aim is to assess the validity, test-retest reliability and responsiveness to change of the FCCI in a longitudinal cohort study of patients with PD. The product of our study will be a reliable and valid measure of the impact of cognitive impairmen on basic and instrumental aspects of daily function. We hypothesize that our new instrument will capture the impact of cognitive impairment on daily function to a greater extent than existing scales used in PD and dementia research. Over the course of the project, we will gain valuable insights into the rate of progression of functional impairment in PDD, and the relative contributions of motor and non-motor features of PD to function over time.